Method to bond concrete slab to metal

ABSTRACT

The method of bonding concrete to a metal substrate eliminates the additional costs in time and labor involved in providing a mechanical bond between concrete and metal surfaces (e.g., construction steel). The method involves the use of an adhesive bonding agent applied between the concrete and metal components that cures to bond the two components together. The method may be used to form a laminar composite deck formed by a concrete slab bonded to a metal deck, a composite joint formed by bonding a concrete slab to a metal beam or joist, and other composite structures.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/694,700, filed Jun. 29, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to construction methods and compositeconstruction materials. More specifically, the present inventioncomprises methods of adhesively bonding concrete to a metal substrate,e.g., construction steel, to form a composite material by chemicalbonding, precluding the need for mechanical attachment. The presentinvention extends to a composite construction material formed by themethod, e.g., a composite deck having a concrete slab chemically bondedto a metal deck or substrate.

2. Description of the Related Art

Steel (or other metals) and concrete have relatively poor adhesion toone another when fresh concrete is poured upon a metal substrate (e.g.,steel construction members, etc.). The relatively weak bond generallyseparates in short order due to differential thermal expansion betweenthe materials, surface corrosion of the metal, etc. No adhesion betweenthe materials exists at all, when a cured concrete element is placedupon a metal substrate. Accordingly, it is conventional in theconstruction trade to provide some form of mechanical attachment betweenthe concrete and steel elements, in the form of indentations,protrusions, and/or small passages formed in the steel members that theconcrete can flow around and through in its plastic state to adhere tothe metal. Such metal elements are known as “Hi-Bond” steel.Alternatively, concrete may be conventionally secured to a metalsubstrate by studs, anchor bolts and the like passing through theconcrete (either before or after curing) and secured to the metalconstruction member.

Both of these general methods of mechanically securing concrete to ametal substrate increase construction costs. In the case of “Hi-Bond”steel, there is additional expense involved in forming the indentations,protrusions, and/or other elements in the steel material in order toprovide the steel with sufficient “tooth” for the concrete to adherethereto. Where such specialized steel is not used, additional materialsand labor are required to set bolts or other anchors into the concreteand steel to attach the concrete and steel components mechanically toone another.

The present inventor is aware of various methods and systems foradhesively securing construction materials to one another. An example isfound in French Patent No. 2,678,658, published on Jan. 8, 1993,describing (according to the drawings and English abstract) differentembodiments of composite panels formed of polystyrene cores having “rockwool” (asbestos) insulation applied to the faces thereof. Thepolystyrene-asbestos composite panels are then adhesively bonded ormechanically secured to a cured concrete slab to provide acoustic andthermal insulation.

None of the above inventions and patents, taken either singly or incombination, is seen to describe the instant invention as claimed. Thusa method of bonding concrete to a metal substrate solving theaforementioned problems is desired.

SUMMARY OF THE INVENTION

The method of bonding concrete to a metal substrate is applicable foradhesively bonding either uncured concrete slurry in its wet, plasticstate or hardened, cured concrete to a metal substrate, e.g.,construction steel. The method involves the application of a bondingagent to the metal substrate and then applying the concrete to thebonding agent coating before the bonding agent cures. In the case of wetconcrete, the bonding agent is allowed to cure partially before theconcrete is poured. In the case of cured concrete, the bonding agent isapplied to the metal substrate (and/or to the surface of the concrete),and the concrete and metal are joined immediately after the applicationof the bonding agent to one or both of the components. The bonding agentdevelops its full adhesive strength between the two materials as itcures. The bonding agent may comprise a two-part epoxy mixture that ismixed immediately before application, the two parts reacting chemicallywith one another for curing. The cured bonding agent may have sufficientresilience to accommodate any differential expansion between thematerials.

These and other features of the present invention will become readilyapparent upon further review of the following specification anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially broken away perspective view of a metal panelhaving an adhesive bonding agent applied thereto in accordance with themethod of the present invention, with a concrete slab partiallyoverlying the metal panel.

FIG. 2 is a partially broken away perspective view of a cured concreteslab applied to an I-beam and bonded thereto according to the method ofthe present invention.

FIG. 3 is a partially broken away perspective view of a prior artmechanical method of securing concrete to a metal panel.

FIG. 4 is a partially broken away perspective view of a prior artmechanical method of securing a cured concrete slab to an I-beam.

FIG. 5 is a flowchart describing the basic steps in the method ofadhesively bonding a wet, plastic concrete slurry to a metal substrate.

FIG. 6 is a flowchart describing the basic steps in the method ofadhesively securing a hardened, cured concrete panel to a metalsubstrate.

Similar reference characters denote corresponding features consistentlythroughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention comprises various embodiments of a method foradhesively bonding concrete to a metal substrate (e.g., metal deckpanel, I-beams, etc.). The method may be applied to either a hardened,cured concrete slab or element, or to the adhesive bonding of a wet,uncured concrete slurry to the metal substrate. The present methodseliminate need for mechanical fastening of the metal to the concrete,thus providing greater economy in the manufacture of the metal and/orthe labor involved in the construction of the metal and concretestructure. While the present methods are particularly well adapted foruse with construction steel, they may be applied to other metals, e.g.,aluminum, copper, etc., as well, for adhesively bonding concretethereto.

The present invention also extends to a composite material useful in theconstruction trades formed by chemically bonding concrete to metal. Anexample of such a composite material is a composite deck formed bybonding a concrete slab to a metal deck. Such a composite deck may forma floor or ceiling in a building or other structure.

The present invention also extends to a joint formed by chemicallybonding concrete to metal. An example of such a joint is a joint betweena concrete slab and an I-beam formed by bonding the concrete to theI-beam with a bonding agent that forms bonds to both the concrete andthe I-beam.

FIG. 1 provides a partially broken away perspective view of a compositeconcrete panel 10 being adhesively bonded to a metal substrate panel 12.While the concrete panel 10 is illustrated as a solid slab, it will beseen that the continuous, unbroken metal deck panel 12 below theconcrete 10 precludes the flow of a wet, uncured concrete slurry throughthe panel 12. Thus, the concrete material 10 may be provided as a wet,uncured slurry, and is shown broken away in FIG. 1 to show theunderlying structure and application of the bonding agent. Reinforcingrods 14 (“rebar”) may be placed over the metal substrate panel 12 priorto pouring the concrete 10 for additional strengthening of the compositeassembly as desired or required.

The adhesive bonding agent 16 may be any bonding agent capable offorming a bond to both concrete and the particular metal used as thesubstrate, usually steel. An example of such an adhesive bondingmaterial 16 is a two part epoxy adhesive material manufactured by theUniversal Form Clamp Co., known by the brand name of Unibond MV®. Thetwo parts of this bonding material are mixed prior to application and,once mixed, react chemically with one another to cure to a hardenedplastic state. However, the bonding material 16 is in a liquid stateprior to and immediately after mixing, prior to its curing reaction. Thebonding material 16 is relatively thin, permitting it to be applied bymeans of a spray gun 18 or the like, or by means of a roller 20 or brush22.

The bonding strength of the adhesive bonding material 16 in its fullycured state may require coating the contact surface(s) 24 of theconstruction material(s) over only a portion thereof, as shown by theareas of bonding material 16 being applied in FIG. 1. However, thecontact surface(s) of the construction material(s) may be completelycoated with the adhesive bonding material 16, as desired or required.The bonding agent 16 is captured between the concrete material 10 andthe metal substrate 12, and develops an adhesive bond between the twomaterials 10 and 12 as the bonding agent 16 develops to a fully curedstate, thereby producing a laminar concrete and metal composite panel.

The bonds formed between the concrete and metal layers have sufficientstrength and resilience that the concrete and metal are securely bondedtogether without slippage between the layers, but will have sufficientstretch that the bonds will not break with expansion and contraction ofthe layers upon variations in temperature within a range that permitsuse of the material in the building and construction trades. While thereis a small degree of bonding that can occur between concrete and metalwithout the use of adhesive or a bonding agent, such bonds are brittleand are typically destroyed by any differential movement between the twolayers, so that no allowance for such bonding is made in the structuralengineering design of buildings and other structures. The compositestructures formed according to the methods of the present invention,however, are able to withstand normal expansion and contraction withoutslippage between the two layers.

The method of the present invention is adaptable for adhesively bondinga wet, uncured concrete slurry to a metal substrate, as noted furtherabove. This is accomplished by first coating only the contact surface 24of the metal substrate 12 with the mixed adhesive bonding agent 16(either partially or completely coating the contact surface, as notedfurther above), and allowing the bonding agent material 16 to curepartially. The curing time will depend upon various factors, e.g., thespecific bonding agent being used, the temperature, and perhaps humidityand/or other factors. A typical partial cure time might be on the orderof three hours or so.

Once the adhesive bonding agent 16 has cured partially to the desiredstate, the wet concrete slurry 10 is poured over the contact surface 24of the metal substrate 12 and its adhesive bonding agent coating 16. Thepartially cured bonding agent material 16 flows slightly and blends withthe immediately adjacent concrete slurry, thereby producing a solidadhesive bond between the concrete and the bonding agent when the twomaterials are fully cured, and with the bonding agent developing a firmadhesive attachment to the underlying metal substrate when the adhesiveagent has fully cured.

This process or method is described generally in the flow chart of FIG.5. Briefly, the method comprises the steps of: coating the metal withadhesive (step 100); allowing the adhesive to partially cure (step 102);applying concrete slurry to the metal (step 104); and allowing theadhesive to cure between the concrete and the metal (step 106).Additional strengthening of the composite concrete and metal structuremay be accomplished as required by conventional mechanical attachment(e.g., rivets or bolts 26, or welding) of additional metal supports,e.g., an I-beam 28, to the metal substrate panel 12, as shown in FIG. 1.

FIG. 2 is an illustration of a somewhat different process, in which theconcrete is first cured to a hardened state prior to adhesively bondingthe concrete to the metal substrate to form a joint between a concreteslab and an I-beam. In FIG. 2, a fully cured, hardened concrete slab 30is bonded to an underlying or adjacent I-beam 28. The cured slab 30 issupported only by the underlying metal structure 28, with no completelyextensive metal substrate panel being provided in the assembly of FIG.2. The concrete slab 30 may be reinforced using rebar elements 14, as isconventional in reinforced concrete structures.

However, rather than attaching the cured concrete slab 30 to the metalsupport structure 28 by conventional mechanical means, an adhesivebonding agent 16 is used. The bonding material 16 is applied to thecontact surface 24 of either the cured concrete slab 30 or the metalsupport 28, or both, as both materials provide a hard surface for theapplication of the liquid adhesive material 16. The adhesive material 16may be applied to a part of the contact surface 24 or to the entiresurface by any conventional means, e.g., spray, roller, or brush, asshown in FIG. 1. In this case, it is not necessary to allow the bondingagent 16 to cure partially, as both structural elements 28 and 30 are ina fully hardened state. Thus, the two elements 28 and 30 may beassembled to one another immediately after the bonding agent 16 has beenapplied to one or the other, or both, of the elements.

It will be noted that the juncture of the cured concrete panel 30 andmetal support structure 28 is devoid of any form of mechanicalattachment or connection, with the adhesive bonding agent 16 providingall of the attachment strength between the two components 28 and 30.This process of adhesively bonding a fully cured concrete slab orelement to a metal structural member is described generally by theflowchart of FIG. 6. Briefly, the method comprises the steps of: coatingthe metal with adhesive (step 110); applying cured concrete to thefreshly coated metal substrate (step 112); and allowing the adhesive tocure between the concrete and the metal (step 114).

FIGS. 3 and 4 illustrate conventional prior art means of securingconcrete and metal elements to one another. In FIG. 3, a “Hi-Bond”construction steel panel S having a series of indentations, protrusions,and/or other irregularities I therein, has a poured reinforced concreteslab C1 resting thereon. The indentations and/or other irregularities Iof the construction steel panel S provide a mechanical grip or “tooth”for the concrete slab Cl to adhere to the panel S as the uncured, fluidconcrete flows around and into the irregularities I as it is poured onthe panel S. Additional mechanical attachment strength between theconcrete slab C1 and the underlying metal panel S may be provided bystuds, bolts or pins P, which pass through the concrete slab C1 and areanchored in the metal panel S, and/or to the underlying I-beam B.

FIG. 4 is an illustration of a prior art assembly of a cured reinforcedconcrete slab C2, which has been mechanically attached to an underlyingI-beam B by means of, studs, bolts or pins P. While the reinforcedconcrete slab C2 is self-supporting in its cured state, conventionalconstruction relies upon mechanical means for the attachment of concreteelements to structural steel elements, generally as shown in FIG. 4.

In conclusion, the present method of adhesively bonding concrete to ametal substrate, greatly simplifies the construction process whereconcrete and steel structures are formed. This simplification of theconstruction process results in various economies during construction,as less costly structural steel may be used and less labor is involveddue to the elimination of mechanical fasteners. The adhesive bondingagents which may be used in accordance with the present method have beenfound to provide more than sufficient strength in such applications, andtheir physical properties can accommodate the thermal expansion andcontraction of the adhesively joined or bonded materials as well asother adverse effects. Accordingly, the present method of bondingconcrete and metal elements together will prove to be quite beneficialto the building and construction trades, and to other fields whereconcrete and metal composite structures are used.

It is to be understood that the present invention is not limited to theembodiments described above, but encompasses any and all embodimentswithin the scope of the following claims.

1. A method of bonding concrete material to a metal substrate material,comprising the steps of: (a) coating at least a portion of the surfaceof either material with a liquid adhesive bonding agent; (b) applyingthe concrete material to the metal substrate material before the bondingagent has cured, capturing the bonding agent coating therebetween; and(c) completely curing the bonding agent coating between the metalsubstrate material and the concrete material, thereby forming a concreteand metal composite.
 2. The method of bonding concrete to a metalsubstrate according to the method of claim 1, further including thesteps of: (a) applying the bonding agent coating only to the metalsubstrate material; (b) allowing the bonding agent coating to curepartially; (c) pouring a wet concrete slurry onto the coated metalsubstrate material; and (d) allowing the bonding agent to blend withadjacent concrete slurry as the bonding agent and concrete slurry curecompletely together.
 3. The method of bonding concrete to a metalsubstrate according to the method of claim 1, further including the stepof applying the concrete material to the metal substrate material in ahardened, fully cured state.
 4. The method of bonding concrete to ametal substrate according to the method of claim 1, further includingthe step of applying the bonding agent to the entire contact surface ofthe material.
 5. The method of bonding concrete to a metal substrateaccording to the method of claim 1, further including the step of mixingthe adhesive bonding agent from two separate parts before application.6. The method of bonding concrete to a metal substrate according to themethod of claim 1, wherein the step of applying the adhesive bondingagent coating comprises spraying, brushing, or rolling the bonding agentonto the material.
 7. The method of bonding concrete to a metalsubstrate according to the method of claim 1, further including the stepof attaching a metal support component to the metal substrate material.8. The method of bonding concrete to a metal substrate according to themethod of claim 7, wherein the step of attaching the metal supportcomponent to the metal substrate material comprises bolting, riveting,or welding.
 9. A laminar composite material, comprising: a layer ofconcrete; a layer of metal; and a bonding agent joining the layers ofconcrete and metal, the bonding agent forming adhesive bonds to theconcrete and adhesive bonds to the metal.
 10. A composite joint,comprising: a slab of concrete; a metal beam; and a bonding agentjoining the slab of concrete and the metal beam, the bonding agentforming adhesive bonds to the concrete slab and adhesive bonds to themetal beam.